Memcached
Memcached
Plugin: go.d.plugin Module: memcached
Overview
Monitor Memcached metrics for proficient in-memory key-value store operations. Track cache hits, misses, and memory usage for efficient data caching.
It reads the server’s response to the stats command.
This collector is supported on all platforms.
This collector supports collecting metrics from multiple instances of this integration, including remote instances.
Default Behavior
Auto-Detection
If no configuration is given, collector will attempt to connect to memcached instance on 127.0.0.1:11211 address.
Limits
The default configuration for this integration does not impose any limits on data collection.
Performance Impact
The default configuration for this integration is not expected to impose a significant performance impact on the system.
Setup
Prerequisites
No action required.
Configuration
File
The configuration file name for this integration is go.d/memcached.conf.
You can edit the configuration file using the edit-config script from the
Netdata config directory.
cd /etc/netdata 2>/dev/null || cd /opt/netdata/etc/netdata
sudo ./edit-config go.d/memcached.conf
Options
The following options can be defined globally: update_every, autodetection_retry.
| Name | Description | Default | Required |
|---|---|---|---|
| update_every | Data collection frequency. | 1 | no |
| autodetection_retry | Recheck interval in seconds. Zero means no recheck will be scheduled. | 0 | no |
| address | The IP address and port where the memcached service listens for connections. | 127.0.0.1:11211 | yes |
| timeout | Connection, read, and write timeout duration in seconds. The timeout includes name resolution. | 1 | no |
Examples
Basic
A basic example configuration.
jobs:
- name: local
address: 127.0.0.1:11211
Multi-instance
Note: When you define multiple jobs, their names must be unique.
Collecting metrics from local and remote instances.
jobs:
- name: local
address: 127.0.0.1:11211
- name: remote
address: 203.0.113.0:11211
Metrics
Metrics grouped by scope.
The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.
Per Memcached instance
These metrics refer to the entire monitored application.
This scope has no labels.
Metrics:
| Metric | Dimensions | Unit |
|---|---|---|
| memcached.cache | available, used | MiB |
| memcached.net | in, out | kilobits/s |
| memcached.connections | current, rejected, total | connections/s |
| memcached.items | current, total | items |
| memcached.evicted_reclaimed | reclaimed, evicted | items |
| memcached.get | hints, misses | requests |
| memcached.get_rate | rate | requests/s |
| memcached.set_rate | rate | requests/s |
| memcached.delete | hits, misses | requests |
| memcached.cas | hits, misses, bad value | requests |
| memcached.increment | hits, misses | requests |
| memcached.decrement | hits, misses | requests |
| memcached.touch | hits, misses | requests |
| memcached.touch_rate | rate | requests/s |
Alerts
The following alerts are available:
| Alert name | On metric | Description |
|---|---|---|
| memcached_cache_memory_usage | memcached.cache | cache memory utilization |
| memcached_cache_fill_rate | memcached.cache | average rate the cache fills up (positive), or frees up (negative) space over the last hour |
| memcached_out_of_cache_space_time | memcached.cache | estimated time the cache will run out of space if the system continues to add data at the same rate as the past hour |
Troubleshooting
Debug Mode
Important: Debug mode is not supported for data collection jobs created via the UI using the Dyncfg feature.
To troubleshoot issues with the memcached collector, run the go.d.plugin with the debug option enabled. The output
should give you clues as to why the collector isn’t working.
-
Navigate to the
plugins.ddirectory, usually at/usr/libexec/netdata/plugins.d/. If that’s not the case on your system, opennetdata.confand look for thepluginssetting under[directories].cd /usr/libexec/netdata/plugins.d/ -
Switch to the
netdatauser.sudo -u netdata -s -
Run the
go.d.pluginto debug the collector:./go.d.plugin -d -m memcached
Getting Logs
If you’re encountering problems with the memcached collector, follow these steps to retrieve logs and identify potential issues:
- Run the command specific to your system (systemd, non-systemd, or Docker container).
- Examine the output for any warnings or error messages that might indicate issues. These messages should provide clues about the root cause of the problem.
System with systemd
Use the following command to view logs generated since the last Netdata service restart:
journalctl _SYSTEMD_INVOCATION_ID="$(systemctl show --value --property=InvocationID netdata)" --namespace=netdata --grep memcached
System without systemd
Locate the collector log file, typically at /var/log/netdata/collector.log, and use grep to filter for collector’s name:
grep memcached /var/log/netdata/collector.log
Note: This method shows logs from all restarts. Focus on the latest entries for troubleshooting current issues.
Docker Container
If your Netdata runs in a Docker container named “netdata” (replace if different), use this command:
docker logs netdata 2>&1 | grep memcached